addnote.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Program to hack in a PT_NOTE program header entry in an ELF file.
  4 * This is needed for OF on RS/6000s to load an image correctly.
  5 * Note that OF needs a program header entry for the note, not an
  6 * ELF section.
  7 *
  8 * Copyright 2000 Paul Mackerras.
  9 *
 10 * Adapted for 64 bit little endian images by Andrew Tauferner.
 11 *
 12 * Usage: addnote zImage
 13 */
 14#include <stdio.h>
 15#include <stdlib.h>
 16#include <fcntl.h>
 17#include <unistd.h>
 18#include <string.h>
 19
 20/* CHRP note section */
 21static const char arch[] = "PowerPC";
 22
 23#define N_DESCR	6
 24unsigned int descr[N_DESCR] = {
 25	0xffffffff,		/* real-mode = true */
 26	0x02000000,		/* real-base, i.e. where we expect OF to be */
 27	0xffffffff,		/* real-size */
 28	0xffffffff,		/* virt-base */
 29	0xffffffff,		/* virt-size */
 30	0x4000,			/* load-base */
 31};
 32
 33/* RPA note section */
 34static const char rpaname[] = "IBM,RPA-Client-Config";
 35
 36/*
 37 * Note: setting ignore_my_client_config *should* mean that OF ignores
 38 * all the other fields, but there is a firmware bug which means that
 39 * it looks at the splpar field at least.  So these values need to be
 40 * reasonable.
 41 */
 42#define N_RPA_DESCR	8
 43unsigned int rpanote[N_RPA_DESCR] = {
 44	0,			/* lparaffinity */
 45	64,			/* min_rmo_size */
 46	0,			/* min_rmo_percent */
 47	40,			/* max_pft_size */
 48	1,			/* splpar */
 49	-1,			/* min_load */
 50	0,			/* new_mem_def */
 51	1,			/* ignore_my_client_config */
 52};
 53
 54#define ROUNDUP(len)	(((len) + 3) & ~3)
 55
 56unsigned char buf[1024];
 57#define ELFDATA2LSB     1
 58#define ELFDATA2MSB     2
 59static int e_data = ELFDATA2MSB;
 60#define ELFCLASS32      1
 61#define ELFCLASS64      2
 62static int e_class = ELFCLASS32;
 63
 64#define GET_16BE(off)	((buf[off] << 8) + (buf[(off)+1]))
 65#define GET_32BE(off)	((GET_16BE(off) << 16U) + GET_16BE((off)+2U))
 66#define GET_64BE(off)	((((unsigned long long)GET_32BE(off)) << 32ULL) + \
 67			((unsigned long long)GET_32BE((off)+4ULL)))
 68#define PUT_16BE(off, v)(buf[off] = ((v) >> 8) & 0xff, \
 69			 buf[(off) + 1] = (v) & 0xff)
 70#define PUT_32BE(off, v)(PUT_16BE((off), (v) >> 16L), PUT_16BE((off) + 2, (v)))
 71#define PUT_64BE(off, v)((PUT_32BE((off), (unsigned long long)(v) >> 32L), \
 72			  PUT_32BE((off) + 4, (unsigned long long)(v))))
 73
 74#define GET_16LE(off)	((buf[off]) + (buf[(off)+1] << 8))
 75#define GET_32LE(off)	(GET_16LE(off) + (GET_16LE((off)+2U) << 16U))
 76#define GET_64LE(off)	((unsigned long long)GET_32LE(off) + \
 77			(((unsigned long long)GET_32LE((off)+4ULL)) << 32ULL))
 78#define PUT_16LE(off, v) (buf[off] = (v) & 0xff, \
 79			  buf[(off) + 1] = ((v) >> 8) & 0xff)
 80#define PUT_32LE(off, v) (PUT_16LE((off), (v)), PUT_16LE((off) + 2, (v) >> 16L))
 81#define PUT_64LE(off, v) (PUT_32LE((off), (unsigned long long)(v)), \
 82			  PUT_32LE((off) + 4, (unsigned long long)(v) >> 32L))
 83
 84#define GET_16(off)	(e_data == ELFDATA2MSB ? GET_16BE(off) : GET_16LE(off))
 85#define GET_32(off)	(e_data == ELFDATA2MSB ? GET_32BE(off) : GET_32LE(off))
 86#define GET_64(off)	(e_data == ELFDATA2MSB ? GET_64BE(off) : GET_64LE(off))
 87#define PUT_16(off, v)	(e_data == ELFDATA2MSB ? PUT_16BE(off, v) : \
 88			 PUT_16LE(off, v))
 89#define PUT_32(off, v)  (e_data == ELFDATA2MSB ? PUT_32BE(off, v) : \
 90			 PUT_32LE(off, v))
 91#define PUT_64(off, v)  (e_data == ELFDATA2MSB ? PUT_64BE(off, v) : \
 92			 PUT_64LE(off, v))
 93
 94/* Structure of an ELF file */
 95#define E_IDENT		0	/* ELF header */
 96#define	E_PHOFF		(e_class == ELFCLASS32 ? 28 : 32)
 97#define E_PHENTSIZE	(e_class == ELFCLASS32 ? 42 : 54)
 98#define E_PHNUM		(e_class == ELFCLASS32 ? 44 : 56)
 99#define E_HSIZE		(e_class == ELFCLASS32 ? 52 : 64)
100
101#define EI_MAGIC	0	/* offsets in E_IDENT area */
102#define EI_CLASS	4
103#define EI_DATA		5
104
105#define PH_TYPE		0	/* ELF program header */
106#define PH_OFFSET	(e_class == ELFCLASS32 ? 4 : 8)
107#define PH_FILESZ	(e_class == ELFCLASS32 ? 16 : 32)
108#define PH_HSIZE	(e_class == ELFCLASS32 ? 32 : 56)
109
110#define PT_NOTE		4	/* Program header type = note */
111
112
113unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
114
115int
116main(int ac, char **av)
117{
118	int fd, n, i;
119	unsigned long ph, ps, np;
120	long nnote, nnote2, ns;
121
122	if (ac != 2) {
123		fprintf(stderr, "Usage: %s elf-file\n", av[0]);
124		exit(1);
125	}
126	fd = open(av[1], O_RDWR);
127	if (fd < 0) {
128		perror(av[1]);
129		exit(1);
130	}
131
132	nnote = 12 + ROUNDUP(strlen(arch) + 1) + sizeof(descr);
133	nnote2 = 12 + ROUNDUP(strlen(rpaname) + 1) + sizeof(rpanote);
134
135	n = read(fd, buf, sizeof(buf));
136	if (n < 0) {
137		perror("read");
138		exit(1);
139	}
140
141	if (memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
142		goto notelf;
143	e_class = buf[E_IDENT+EI_CLASS];
144	if (e_class != ELFCLASS32 && e_class != ELFCLASS64)
145		goto notelf;
146	e_data = buf[E_IDENT+EI_DATA];
147	if (e_data != ELFDATA2MSB && e_data != ELFDATA2LSB)
148		goto notelf;
149	if (n < E_HSIZE)
150		goto notelf;
151
152	ph = (e_class == ELFCLASS32 ? GET_32(E_PHOFF) : GET_64(E_PHOFF));
153	ps = GET_16(E_PHENTSIZE);
154	np = GET_16(E_PHNUM);
155	if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
156		goto notelf;
157	if (ph + (np + 2) * ps + nnote + nnote2 > n)
158		goto nospace;
159
160	for (i = 0; i < np; ++i) {
161		if (GET_32(ph + PH_TYPE) == PT_NOTE) {
162			fprintf(stderr, "%s already has a note entry\n",
163				av[1]);
164			exit(0);
165		}
166		ph += ps;
167	}
168
169	/* XXX check that the area we want to use is all zeroes */
170	for (i = 0; i < 2 * ps + nnote + nnote2; ++i)
171		if (buf[ph + i] != 0)
172			goto nospace;
173
174	/* fill in the program header entry */
175	ns = ph + 2 * ps;
176	PUT_32(ph + PH_TYPE, PT_NOTE);
177	if (e_class == ELFCLASS32)
178		PUT_32(ph + PH_OFFSET, ns);
179	else
180		PUT_64(ph + PH_OFFSET, ns);
181
182	if (e_class == ELFCLASS32)
183		PUT_32(ph + PH_FILESZ, nnote);
184	else
185		PUT_64(ph + PH_FILESZ, nnote);
186
187	/* fill in the note area we point to */
188	/* XXX we should probably make this a proper section */
189	PUT_32(ns, strlen(arch) + 1);
190	PUT_32(ns + 4, N_DESCR * 4);
191	PUT_32(ns + 8, 0x1275);
192	strcpy((char *) &buf[ns + 12], arch);
193	ns += 12 + strlen(arch) + 1;
194	for (i = 0; i < N_DESCR; ++i, ns += 4)
195		PUT_32BE(ns, descr[i]);
196
197	/* fill in the second program header entry and the RPA note area */
198	ph += ps;
199	PUT_32(ph + PH_TYPE, PT_NOTE);
200	if (e_class == ELFCLASS32)
201		PUT_32(ph + PH_OFFSET, ns);
202	else
203		PUT_64(ph + PH_OFFSET, ns);
204
205	if (e_class == ELFCLASS32)
206		PUT_32(ph + PH_FILESZ, nnote);
207	else
208		PUT_64(ph + PH_FILESZ, nnote2);
209
210	/* fill in the note area we point to */
211	PUT_32(ns, strlen(rpaname) + 1);
212	PUT_32(ns + 4, sizeof(rpanote));
213	PUT_32(ns + 8, 0x12759999);
214	strcpy((char *) &buf[ns + 12], rpaname);
215	ns += 12 + ROUNDUP(strlen(rpaname) + 1);
216	for (i = 0; i < N_RPA_DESCR; ++i, ns += 4)
217		PUT_32BE(ns, rpanote[i]);
218
219	/* Update the number of program headers */
220	PUT_16(E_PHNUM, np + 2);
221
222	/* write back */
223	i = lseek(fd, (long) 0, SEEK_SET);
224	if (i < 0) {
225		perror("lseek");
226		exit(1);
227	}
228	i = write(fd, buf, n);
229	if (i < 0) {
230		perror("write");
231		exit(1);
232	}
233	if (i < n) {
234		fprintf(stderr, "%s: write truncated\n", av[1]);
235		exit(1);
236	}
237
238	exit(0);
239
240 notelf:
241	fprintf(stderr, "%s does not appear to be an ELF file\n", av[1]);
242	exit(1);
243
244 nospace:
245	fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
246		av[1]);
247	exit(1);
248}